Bifilar polyamide yarns and filaments



United States Patent US. Cl. 161-173 8 Claims ABSTRACT OF THE DISCLOSURE Bifilar yarns and filaments having a wool like crimp comprising a polyamide filament composed of (a) an unmodified polyamide component and (b) a polyamide component containing 0.5 to of a sulfonic acid segment having the formula:

wherein R" is a (CH group, a cyclohexylene group or the group x and y are each integers of from 2 to 12, R is hydrogen or the group (CH SO Me, wherein 1 has a value of from 4 to 6 and Me is an alkali metal or hydrogen and R is (CH SO Me wherein z and Me are as just defined.

The described filaments are formed by melt spinning a polyamide having the component as set out above in (b) together with an unmodified polyamide component (a) at a temperature of from 250 to 300 C., stretching the filaments thus obtained and treating the stretched filaments at elevated temperatures with water.

This application is a continuation of our earlier filed application, Ser. No. 455,579, filed May 13, 1965, now abandoned.

This invention relates to polyamide yarns, filaments, fibres and threads having a wool-like crimp and to a process for the production of these polyamide yarns.

Polyamides obtained by the condensation of ammonium salts of dicarboxylic acids with diamines or by the homocondensation of e-aminocarboxylic acids, and also by polymerization of higher-membered lactams can be spun from the melt in known manner to form filaments and fibres. After the stretching or drawing thereof, smooth filaments and fibres are obtained which do not have any wool-like crimping. In order to obtain crimped products, the filaments must be treated mechanically, for example by compression crimping. A disadvantage with these mechanical methods is that the fibres can very easily be damaged by mechanical action, and that such a crimping disappears in the course of time as a result of unskilled treatment. more been proposed to spin two different polyamide components in bifilar form, that is to say, into a composite filament. These two components are distinguished in the structure of their dicarboxylic acids and/or diamines by a different number of carbon atoms. One such pair is for example the polyamide of poly-e-aminocarproic acid and Get:

the polyamide of hexamethylene diamine and adipic acid of sebacic acid, i.e. the polyamide of e-aminocaproic acid or of hexamethylene diamine and adipic acid is spun in bifilar form alongside the polyamide of hexamethylene diamine and sebacic acid. After the bifilar spinning, the filaments thus obtained are drawn and then treated at high temperature in water. A crimping is produced on account of the different shrinkage on boiling of the two bifilar polyamide components. The intensity of the crimping is determined by the difierence in the shrinkage shown by the two components on boiling, and it is greater as the difference in the shrinkage on rboiling is greater. The crimping efiects thus obtained are more or less irreversible, i.e. if the crimping is removed by too strong an elo-ngation, it is normally not possible for a crimped wool-like character successfully to be obtained again by treatment with cold water.

An object of this invention is to provide a process for the production of yarns, filaments, fibres and threads from polyamides having a wool-like crimping, which comprises spinning aliphatic polyamides containing sulphonic acid groups with polyamides in bifilar form, i.e. into a composite filaments. After the drawing, heating in water or steam and drying, filaments or fibres are obtained which assume a helically crimped character similar to wool.

It is therefore possible by this process for an only slightly modified polyamide to be spun in bifilar form alongside its unmodified polyamide to yield subsequently crimped wool-like filaments or fibres.

The aliphatic polyamides containing sulphonic acid groups are obtained 'by admixing N,N'-disulphoalkyl alkylene diamines or N-monosulphoalkyl alkylene diamines of the general formulae or H NR"NH(CH ),,SO Me, wherein R" is a (CH ),,group, a cyclohexylene group or the group x represents the numbers 2 to 12, y the numbers 4 to 6 and Me represents hydrogen or an alkali metal, with approximately equivalent quantities of alkylene dicarboxylic acids or their alkali salts in quantities up to 25% by weight of polyamide-forming starting materials (such as lactams or salts of diamines and dicarboxylic acids) the reaction mixture being polycondensed and the polyamides obtained being spun from the melt into filaments or fibres.

In one particular embodiment, 0.5 to 20% and advantageously 1.5 to 10% of the following structural element wherein R" is the group (CH a cyclohexylene group or the group x and y represent an integer from 2 to 12, R and R represent hydrogen or the group -(CH SO M (2:4 to 6, Me=an alkali metal or hydrogen), are contained in the chain.

Polyamides which can be used include those produced from lactams, for example from e-caprolactam, and also from w-aminocarboxylic acids (such as e-aminocaproic acid and ll-aminoundecanic acid) and from the diammonium salts of alkylene diamines with dicarboxylic acids (for example the salts of tetra-, hexa-, octamethylene diamine with adipic acid, suberic acid and sebacic acid).

Examples of diaminosulfonic acids suitable for the process of this invention are for example:

For example, 5% of the structural units are incorporated by condensation into caprolactam, e-aminocaproic l acid, w-aminoundecanoic acid or into ammonium salts of alkylene dicarboxylic acids with alkylene diamines. These latter include for example the combinations of hexamethylene diamine and adipic acid, octamethylene diamine and adipic acid, hexamethylene diamine and sebacic acid etc.

The sulfoalkyl diamine starting reactants can be prepared by the method described in copending application Ser. No. 420,438. Thus the sulfoalkyl diamines and specifically N-(w-aminoalkylene)-aminoalkyl sulfonic acids are obtained by reacting an alkylene (ii-primary amine having about 2 to 12 carbon atoms in the alkylene group with an alkyl sultone'wherein the alkyl group contains about 3 to 7 carbon atoms at temperatures from -20 to +100 C. The reaction can be effected in the presence of a solvent and namely an aromatic or halogenated hydrocarbon solvent. The reaction takes place according to the following equation:

It is of course also possible for a suitable modified type of polyamide to be spun in bifilar form with an unmodified polyarnide of different molecular composition. Included herein is for example the combination of polyamide of hexamethylene diamine and sebacic acid alongside the modified polyamide containing sulphonic acid groups from caprolactam. Also copolyamides for example a copolyamide of caprolactam and the diammonium salt of hexamethylene diamine terephthalic acid and can be used profitably.

The bifilar composite filament is obtained by separately melting the modified polyamide components produced in this way and the unmodified copolyamides and by spinning both together at temperatures between 250 and 300 C., advantageously 265 to 285 C., in such a way that both components adhere to one another throughout the length of the filament. The ratios by weight between the two spun components are advantageously between :1 and 1:5.

The bifilar composite filaments thus obtained are then drawn at room temperature or at a higher temperature. The drawing temperature itself depends on the composition of the polyamides and is normally between and +140 C. The filaments are then subjected to a heat treatment with water at temperatures of about 60 to 120 C., a crimping being indicated in the moist state, due to the different shrinkage of the components of the composite filament on boiling. The heat treatment may be effected with hot water or steam. The strength of the crimping depends on the difference in the hydrophilic properties of the two bifilar-spun polyarnides as well as on the shrinkage on boiling. In the drawing operation, the hydrophilic proportion of the bifilar filament now shrinks to a far greater degree, so that in this way an extraordinarily intensive and uniform three-dimensional crimping occurs and the product is given a character similar to wool. When these filaments are placed in cold or warm water, the more hydrophilic constituent of the bifilar filament absorbs substantially more moisture than the hydrophobic constituent, so that thereby a more or less strong disappearance of the crimping is caused. On renewed drying, the prior crimping condition is however obtained again in practice. This process can be repeated as desired without the initially supplied crimping eifect being lost, even in its intensity. Even if the shrinkage on boiling is removed by strong over-stretching, the prior crimping e'ifect can be restored completely after heating in tepid water, that is to say, the crimping effect is reversible in all cases.

A further crimping effect is produced by subjecting the stretched bifilar filaments to a thermal treatment, at a temperature range of between 120 to 180 C., for example by hot air, and this crimping is not removed by treatment with water. If the filaments treated in this way are additionally introduced into hot water, a reversible crimping caused by hot water is added to the crimping which already exists. In addition, the bifilar fibres produced in this way can be dyed very easily with basic dyestuffs and they even have a very good light fastness.

The following examples illustrate more specifically the invention and describe specific embodiments of the invention.

EXAMPLE 1 Unmodified poly-e-aminocaproic acid, a 1% solution in m-cresol at 25 C. of which had a relative solution viscosity of 2.7 and a modified poly-e-aminocaproic acid with 5% of the structural unit and produced from the compound NH(CH --NH- (CH %O H and acid sodium adipate with the same relative solution viscosity, were spun at 280 C. in air at a temperature of 25 C. into a bifilar composite filament. The spinning pumps were so adjusted that the ratio by weight of the initial quantities of the unmodified and modified components was 1:1. Using a withdrawal velicity of 800 1:1./min. and a l2-aperture spinneret with an aperture diameter of 0.25 mm., a multifilar filament was produced and this was stretched in the ratio of 123.5 between two plates at a temperature of C. On treatment with hot water at C. and drying in the relaxed state, this filament developed an intensive helical crimping.

EXAMPLE 2 As in Example 1, a multifilament of composite filaments was produced, the ratio of the starting quantities of the two components being 1 part by weight of unmodified and 2 parts by weight of modified poly-e-aminocaproic acid.

EXAMPLE 3 Bifilar composite filaments were spun from the components of Example 1 at a spinning temperature of 280 C. with a velocity of 400 m./min. and these composite filaments, after stretching in the ratio of 1:4 between hot plates at a temperature between 20 and 180 C., had an individual count of 15 denier. The ratio between the initial quantities of the two components was 1:1. The helical crimping developed according to Example 1 was characterized by comparison with the 5 denier filament of Example 1, by a lower number of crimps (number of twists, per cm.) and a larger diameter of the crimping helices.

EXAMPLE 4 Under the conditions described in Example 1, poly-eaminocaproic acid and a modified poly-e-aminocaproic acid, which contained 5% of the structural unit N(oHi)iNi':' Cum-h-- SO Na s Na produced from the compound and neutral sodium adipate, were spun in bifilar form in the quantitative ratio of 1:2 into composite filaments. After stretching or drying at 95 C. in the ratio of 123.8, the filaments treated withd hot water at a temperature of 100 C. showed a stronger helical crimping than the filaments which were described in Example 1.

EXAMPLE 5 As in Example 1, a multifilament was produced-with a polyamide having 2.5% by weight of the sulfonic acid segmentthe ratio of modified polamide to the normal polyamide was 1:2. After stretching in the ratio 123.9 at 95 C. the titer of the filaments was 15 den. and after treatment with water at 95 C., the obtained bifilar filament shows a crimping effect according to the bifilar filament of Example 1.

EXAMPLE 6 According to Example 1with a polyamide having by weight of the sulfonic acid segment-was prepared a multifilament (ratio by weight 1:1). After stretching at 150 C. (1:3.75) the titer was den. On treatment with water at 85 C., this bifilar filament shows a regular and fine crimping.

EXAMPLE 7 A modified polyamide of E-aminocaproic acid, which contains in the chain up to 5% of the structural unit a 1% solution of which m-cresol at 25 C. has a relative solution viscosity of 2.65, is spun alongside unmodified poly-e-aminocaproic acid of the same relative solution viscosity at a spinning head temperature of 275 C. into air of 25 C. to form a bifilar composite filament. Using a withdrawal velocity of 780 m./min. and a 12-aperture spinneret and an aperture diameter of 0.25 mm., a multifilar filament is obtained, in which the two components are present in the ratio of 1:1. The filament is stretched between plates at 85 C. in the ratio of 1235. After treatment with hot water at temperatures of 90 C. the filament is dried in the relaxed condition and thereby develops an intensive helical crimping.

EXAMPLE 8 From the components indicated in Example 1, a multifilament is produced under the same conditions, and by altering the spinning pump velocity, the ratio between modified and unmodified polyamides is kept at 2:1. After treatment as in Example 1, an intensively crimped filament is obtained.

EXAMPLE 9 Under the conditions as indicated in Example 1, polye-aminocaproic acid was spun in bifilar arrangement alongside a polyamide containing 8% of the structural unit and in the ratio' of 1:2. After stretching at 95 C. in the ratio of 123.7, the filaments treated with hot water at a temperature of 100 C. and dried show a strong helical crimping.

EXAMPLE 10 As in Example 1, poly-e-aminocaproic acid is spun alongside poly-e-aminocaproic acid which contains up to 4.5% of the structural unit H) so Na (CH2)4.SO Na and in the ratio of 1:1 into bifilar composite filaments. The filaments stretched at C. in the ratio 123.8 are treated with hot water at a temperature of C. and dried and then show an intensive helical crimping.

What is claimed is:

1. A bifilar yarn and filament having a wool like crimp, consisting essentially of (a) an unmodified polyamide component and (b) a polyamide component containing 0.5 to 20% based on the polymer of a sulfonic acid segment of the formula:

wherein R" is a member selected from the group consisting of -(CH cyclohexylene and x and y each represent an integer from 2 to 12, R represents a member selected from the group consisting of hydrogen and (CH -SO Me wherein z has a value of 4 to 6 and Me is a member of the group of alkali metals and hydrogen and R represents (CH -SO Me wherein z and Me are as above defined.

2. Yarn and filament according to claim 1 wherein said unmodified polyamide component (a) is present in a weight ratio with respect to said polyamide component (b) of from 1:5 to 5:1.

3. Yarn and filament according to claim 1 wherein said polyamide component (b) contains 1.5 to 10% based on the polymer of said sulfonic acid segment.

4. A bifilar yarn and filament according to claim 1 consisting essentially of unmodified poly-e-aminocaproic acid and poly-s-aminocaproic acid containing 5% based on the polymer of a segment of the formula:

0 NH(CH2)aN -(CH2)4 (CHz)4SO Na 5. A bifilar yarn and filament according to claim 1 consisting essentially of unmodified poly-e-aminocaproic acid and poly-e-aminocaproic acid containing 5% based on the polymer of a segment of the formula:

acid and poly-s-aminocaproic acid containing 5% based on the polymer of a segment of the formula:

7. A bifilar yarn and filament according to claim 1 consisting essentially of unmodified poly-e-aminocaproic acid and poly-e-aminocaproic acid containing 5% based on the polymer of a segment of the formula:

' 7 8 8. A bifilar yarn and filament according to claim 1 References Cited copsisting essentiallypf unr nodii ied poly-e aminocaproic UNITED STATES PATENTS and and poly-e-ammocaprolc ac1d contammg 5% based on the polymer of a segment of the formula: 2,989,798 6/1961 Bannel'man- 3,182,100 5/1965 Bedell.

5 3,225,534 12/1965 Knospe.

C C HAROLD D. ANDERSON, Prlmary Exammer E US. Cl. X.R.

CERTIFICATE OF CORRECTION Pateflf No, Dated April 7,

Inventofls) HARRY IEI K, FERDINAND BODESHEIM, G'U'NTHER NAWRA'L'H, AL .0 an CHK It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

I' Column 1, line 66, after "ment." insert --In order to obtain crimped polyamides, it has furthercolumn 2, line 23, "filaments" should be --filament--; column 4, -line 34, "velicity" should be --velocity--; column 5, line 4, "withd" should be --with-- SIGNED AND SEALED sips-197p 48m) AM Ed I WIILIAM E- BGHUYIIER.

M Jr. Comissioner of Patents Aztesting Officer I 

